Preparation and properties of waterborne poly(urethane urea)s for adhesives: The effects of the 2,2‐bis(hydroxylmethyl)propionic acid content on the properties

Abstract

A series of waterborne poly(urethane urea)s (WBPUs) containing various concentrations (8.3-15.5 mol %) of 2,2-bis(hydroxylmethyl)propionic acid (DMPA) were prepared from isophorone diisocyanate, poly(tetramethylene adipate) glycol, DMPA, ethylenediamine, and triethylamine. The length of the hard segment with the DMPA content was varied from 18.7 to 22.6 wt % at a fixed soft-segment length (2000 g/mol). The effect of the DMPA content on the colloidal properties of WBPU dispersions, the hydrogen-bonding index, water swelling, dynamic mechanical thermal properties, and mechanical properties of WBPU films, and the adhesive strengths of substrates such as chloroprene rubber (CR)/CR, CR/polyurethane foam, CR/ethylene vinyl acetate foam, and thermoplastic olefin sheet/polypropylene foam were investigated. Stable aqueous dispersions of WBPU were obtained when the DMPA concentration was greater than 10 mol %. As the DMPA content increased, the particle size of the WBPU dispersion decreased, but the viscosity of the WBPU dispersion increased. The hydrogenbonding fraction, water swelling, dynamic storage modulus and relaxation temperature, and tensile strength of the films increased with increasing DMPA content. According to an adhesion test, the substrates adhering to WBPU with greater than 10 mol % DMPA tore at about 8.0 kgf/cm 2 instead of breaking the adhered region. These results suggested that the WBPUs prepared in this study could have potential for adhesive use.

Synthesis and characterization of waterborne polyurethane adhesives containing different amount of ionic groups (I)

“…26 Kwak et al in previous work showed that the tensile strength and initial modulus increased with increased of DMPA content, same behavior also observed here. Figure 9 shows the relationship between the pressing temperature and the adhesive strength of WBPU dispersions with various DMPA content when the testing condition was room temperature.…”

“…Previous studies [22][23][24][25][26] have demonstrated that increase in the ionic group content increases the viscosity of the polyurethane dispersion. By increasing the DMPA content, the mean particle size decreased from $ 86 to 42 nm, but the viscosity increased from 75 to 3302 cps at 258C.…”

Waterborne Polyurethane from Polycaprolactone and Tetramethylxylene Diisocyanate: Synthesis by Varying NCO/OH Ratio and Its Characterization as Wood Coatings

“…In order to disperse in water, ionic group needs to be incorporated in the polyurethane structure. PUD consists of both soft and hard segments [7]. The hard segment consists of isocyanate and chain extenders whereas the soft segment consists of polyol.…”

Preparation and properties of waterborne polyurethane-silane: A promising antifouling coating

“…WBPUs are now being widely used as coating and adhesive materials in the automotive, construction, textiles, paper, and footwear industries. 1,2 However, there are some challenges with the use of WBPU due to less mechanical strength, less thermal stability and less adhesive strength. To improve these properties, significant efforts have been made during the last decade with various approaches such as using a higher 2,2-dimethylol propionic acid (DMPA) content, using poly(tetramethylene adipate glycol), incorporating an aliphatic hardener, blending and crosslinking.…”